Tile Drains A Comparison of Surface & Subsurface Drainage

1. Tile Drains A Comparison of Surface & Subsurface Drainage Haleahy Craven, Jonathan Farmer, Reese Freeman, & Dan Maddock

2. Tile Drains? • little information in VT • issues with runoff during heavy rain/snowmelt • rows of perforated piping below ground • allows water percolation to avoid saturation of soil • absorption of nutrients by plant roots

4. Our Goals • To determine whether regulation on tile drains is necessary • Provide DEC with: • data on whether there is a significant difference in nutrient loading to surface waters • influential site characteristics • management recommendations

5. Justification • extremely little data/info about tile drain in VT • originally implemented due to increased crop yield • little consideration to nutrient & sediment loading

6. Controlled Drainage Experiments Overview • 3 separate experiments on controlled vs conventional (free) drainage. - Sites included southwestern Ontario, Quebec, and Sweden • The Canadian experiments used a controlled drainage/subirrigation system • Swedish experiment was only controlled drainage with no subsurface irrigation

7. Controlled Drainage Highlights Total P Loads in Free and Controlled Drainage • Quebec Phosphorus loads - Increased P loads in drainage from controlled drainage compared to free drainage - Drainage outflow volume was reduced in controlled drainage - Majority was dissolved P Caroline Sanchez Valero, Chandra A. Madramootoo, Nicolas Stämpfli

8. Controlled Drainage Highlights Cont. • Ontario Nitrate Loss - cumalituive draiange water volume was slightly greater in controlled system - flow weighted mean nitrate concentration was reduced in controlled (41%) • Corn Yields - Soil moisture content was greater in controlled and water table was not as deep as compared to free drainage system - Yields increased by about 60% Nitrate in Drainage H.Y.F. Ng, C.S. Tan, C.F. Drury, J.D. Gaynor

9. Controlled Drainage Highlights Cont. Grain Yields and N uptake • Sweden N Loses - Reduced outflow rate in controlled system - High risk periods for N losses - Increased N uptake • P loses - Conventional system - Controlled system Ingrid Wesström, Ingmar Messing

10. Controlled Drainage Conclusions • In most cases outflow volume is reduced in controlled systems • Peak loading in regards to N and P occur during high outflow rates • Increased N uptake as well as other factors, increased crop yields • P seems a bit more unpredictable • Better alternative to conventional • Issues - Difficult to figure out how exactly system was controlled - There seems to be a lot of site specificity - How will experiments in VT look?

11. Soil Structure • Macropore Systems • macroinvertebrates • root canals • cracking marine clay soils • Preferential flow • Reduces nutrient uptake by plants and soils • Increases nutrient leaching and sediment loading to surface waters

13. Soil Structure Management • Conventional Ploughing • Shallow Till • No till • Structural Liming • Quicklime • Clay-2H+ + CaO → Clay -Ca2+ + H2O • Slaked Lime

15. Fertilization Techniques • Broadcast fertilization • Placement or Injection fertilization • Reduces losses in non-growing season and cold weather climates

16. DRP vs Pdop • DRP - Dissolved Reactive Phosphorus • Readily available to aquatic organisms • Pdop - Dissolved Organic Phosphorus + Particulate • Pt - Total Phosphorus

17. and Recommendations for Site Specific Studies & Management Practices in Vermont Considerations...

18. The Effects of Tile Drains are Site Specific • Site Characteristics - soil - climate • History - Joshua Faulkner: study on past tile drain activity * Recommendations - complete GIS map of present tile drains - GIS climate and soil data handouts

19. Proper Management is Essential! • Care for Soil Structure - soil can change - cracks are bad • Tilling Preferences - tilling changes soil structure • Fertilization - green manure can leach - injection or place based methods - Timing is Everything! * Recommendations - subsurface drainage should be included into a farm’s management plan - a reviewed management plan and routine checkups based on site conditions could be required for subsurface tile drains (a review board may need to be created) - controlled drainage is generally prefered Poor management is bad!

20. What we did not find... Alternative Impacts • Hydrologic Cycle - Groundwater Recharge - Nearby Communities and Ecosystems • Future Site Goals - Developement - Remediation - Reclamation • Impacts of Climate Change? • Clay Soil Map of Vermont * Recommendations - No drain zones?

21. THE ENNNNNNDDD...